Messages in this thread Patch in this message | | | From | Deepak Gupta <> | Subject | [PATCH v1 RFC Zisslpcfi 03/20] riscv: zisslpcfi extension csr and bit definitions | Date | Sun, 12 Feb 2023 20:53:32 -0800 |
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zisslpcfi extension extends xstatus CSR to hold enabling bits for shadow stack, forward cfi (landing pad instruction enforcement on indirect call/jmp) and recording current landing pad state of cpu.
zisslpcfi adds two new CSRs - CSR_LPLR: Strict forward control flow can be implemented by compiler by doing label match on target with label generated on call-site. This CSR can be programmed with label (preserving current abi). New instrs are provided to place label values in this CSR. - CSR_SSP: Return control flow is protected via shadow stack. CSR_SSP contains current shadow stack pointer.
Signed-off-by: Deepak Gupta <debug@rivosinc.com> --- arch/riscv/include/asm/csr.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 0e571f6483d9..243031d1d305 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -18,6 +18,23 @@ #define SR_MPP _AC(0x00001800, UL) /* Previously Machine */ #define SR_SUM _AC(0x00040000, UL) /* Supervisor User Memory Access */ +/* zisslpcfi status bits */ +#define SR_UFCFIEN _AC(0x00800000, UL) +#define SR_UBCFIEN _AC(0x01000000, UL) +#define SR_SPELP _AC(0x02000000, UL) +#define SR_MPELP _AC(0x04000000, UL) +#ifdef CONFIG_RISCV_M_MODE +#define SR_ELP SR_MPELP +#else +#define SR_ELP SR_SPELP +#endif + +#ifdef CONFIG_RISCV_M_MODE +#define CFISTATUS_MASK (SR_UFCFIEN | SR_UBCFIEN | SR_MPELP | SR_SPELP) +#else +#define CFISTATUS_MASK (SR_ELP | SR_UFCFIEN | SR_UBCFIEN) +#endif + #define SR_FS _AC(0x00006000, UL) /* Floating-point Status */ #define SR_FS_OFF _AC(0x00000000, UL) #define SR_FS_INITIAL _AC(0x00002000, UL) @@ -168,6 +185,14 @@ #define ENVCFG_CBIE_INV _AC(0x3, UL) #define ENVCFG_FIOM _AC(0x1, UL) +/* + * zisslpcfi user mode csrs + * CSR_LPLR is a label register which holds compiler generated label that must be checked on target. + * CSR_SSP holds current shadow stack pointer. + */ +#define CSR_LPLR 0x006 +#define CSR_SSP 0x020 + /* symbolic CSR names: */ #define CSR_CYCLE 0xc00 #define CSR_TIME 0xc01 -- 2.25.1
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